Heat stress impairs proprioception but not running mechanics.

Autor: Mtibaa K; Qatar University, Sports Science Program, College of Arts and Sciences, Doha, Qatar; Inter-university Laboratory of Human Movement Biology (EA 7424), Claude Bernard University Lyon 1, Lyon, France., Zarrouk N; Aspetar Orthopaedic and Sports Medicine Hospital, Doha, Qatar., Girard O; Aspetar Orthopaedic and Sports Medicine Hospital, Doha, Qatar; Murdoch Applied Sports Science (MASS) Laboratory, Murdoch University, Perth, Australia., Ryu JH; Aspire Academy, Doha, Qatar., Hautier C; Inter-university Laboratory of Human Movement Biology (EA 7424), Claude Bernard University Lyon 1, Lyon, France., Racinais S; Aspetar Orthopaedic and Sports Medicine Hospital, Doha, Qatar. Electronic address: sebastien.racinais@aspetar.com.
Jazyk: angličtina
Zdroj: Journal of science and medicine in sport [J Sci Med Sport] 2019 Dec; Vol. 22 (12), pp. 1361-1366. Date of Electronic Publication: 2019 Jul 24.
DOI: 10.1016/j.jsams.2019.07.008
Abstrakt: Objectives: To determine the effects of heat stress on ankle proprioception and running gait pattern.
Design: Counterbalanced repeated measures.
Methods: 12 trained runners performed a proprioception test (active movement discrimination) before and immediately after a 30min, self-paced treadmill run in HOT (39°C) and COOL (22°C) ambient conditions. Velocity was imposed during the first and last minute (70% of maximal aerobic velocity, 13.3±0.8kmh -1 ) for determination of running mechanics and spring-mass characteristics.
Results: Rectal (39.7±0.4 vs. 39.4±0.4°C), skin (36.3±1.1 vs. 31.8±1.1°C) and average body (38.3±0.2 vs. 36.4±0.4°C) temperatures together with heart rate (178±8 vs. 174±6bpm) and thermal discomfort (6.5±0.5 vs. 4.3±1.3) were all higher at the end of the HOT compared to COOL run (all p<0.05). Distance covered was lower in HOT than COOL (-5.1±3.6%, p<0.001). Average error during the proprioception test increased after running in HOT (+11%, p<0.05) but not in COOL (-2%). There was no significant difference for most segmental and joint angles at heel contact, except for a global increase in pelvis retroversion and decrease in ankle dorsi-flexion angles with time (p<0.05). Step frequency decreased (-2.5±3.6%) and step length increased (+2.6±3.8%) over time (p<0.05), independently of condition. Spring-mass characteristics remained unchanged (all p>0.05).
Conclusions: Heat stress exacerbates thermal, cardiovascular and perceptual responses, while running velocity was slower during a 30min self-paced treadmill run. Heat stress also impairs ankle proprioception during an active movement discrimination task, but it has no influence on gait pattern assessed at a constant, sub-maximal velocity.
(Copyright © 2019 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.)
Databáze: MEDLINE
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